In recent years, as seen in a sick house/sick building syndrome and the like, a damage to person's health due to formaldehyde or the like has attracted attention. It is known that, as a method for removing aldehyde gas in an indoor environment, an aldehyde removing agent comprising an amine compound is effective. Aldehyde gas is a collective name covering aldehyde compounds volatile at normal temperature, including formaldehyde and acetaldehyde as representative examples.
For example, Patent Document 1 discloses that exhaust gas containing aldehyde gas is contacted with a liquid having an amine compound dissolved therein to remove aldehyde gas in the exhaust gas. However, an amine compound in the liquid state has a strong unpleasant odor, and therefore is unsuitable for the application to a daily life, such as a living space including, for example, a living room or a kitchen.
For solving the above problem, an aldehyde gas absorbent comprising an amine compound and an inorganic material having supported thereon the amine compound has been known, and Patent Document 2 discloses a deodorizing adsorbent comprising an amino group-containing silane coupling agent and a porous metal oxide, such as silica, alumina, titania, or zirconia, having supported thereon the silane coupling agent and has a description that the adsorbent can be used in a filter for an air cleaner or the like. In the working Examples, there is a description showing that the silane coupling agent was supported on a silica carrier and subjected to evaporation to dryness at 120° C., but the aldehyde deodorizing ability is not satisfactory.
Further, Patent Document 3 discloses an aminoguanidine compound as a chemical agent for removing an aldehyde. However, the aminoguanidine compound is in the form of a hydrochloride or sulfate which is a strong acid, and hence has problems in that when such a strongly acidic compound is in contact with a metal during the processing or use thereof, the metal suffers corrosion, and in that when the acidic compound is spread using a binder, discoloration occurs.
A number of aldehyde gas deodorants have been proposed in which the deodorants comprise a hydrazine compound as a compound which is almost neutral and is easily reacted with an aldehyde, and an inorganic compound carrier having supported thereon the hydrazine compound. For example, Patent Document 4 discloses an aldehyde gas deodorant comprising hydrated hydrazine and porous silicon dioxide or aluminum silicate having supported thereon the hydrated hydrazine. Further, Patent Document 3 discloses an aldehyde gas deodorant obtained by supporting succinic dihydrazide, carbohydrazide, or oxalic dihydrazide on aluminum silicate and magnesium silicate by heating at 140° C. to 220° C. These aldehyde gas deodorants comprising a hydrazine compound and an inorganic compound having supported thereon the hydrazine compound are excellent in processability and aldehyde deodorizing effect; however, these deodorants do not satisfactorily care about the safety of a human body.
Specifically, the above Patent Documents have no description about the mutagenicity with respect to the above-mentioned aldehyde gas deodorants. It is known that, for example, hydrated hydrazine itself is a substance which is strongly positive for mutagenicity. Therefore, the aldehyde gas deodorant using such a hydrazine is considered to be positive for mutagenicity, and is not regarded as a satisfactorily safe aldehyde gas deodorant to be used in a living space. On the other hand, with respect to succinic dihydrazide, it is known that the substance itself is weakly positive for mutagenicity, and it has been considered that succinic dihydrazide is acceptable as an aldehyde gas deodorant used in a living space. However, the present inventors have found the problem that when an inorganic compound carrier having succinic dihydrazide supported thereon is heated, the mutagenicity becomes positively increased.
Further, it has been known that, among the hydrazine compounds as a chemical agent for removing an aldehyde, carbohydrazide, oxalic dihydrazide, and adipic dihydrazide are negative for mutagenicity. For example, Patent Document 5 discloses an aldehyde gas deodorant obtained by mixing 40 g of adipic dihydrazide in the form of an aqueous solution with 80 g of silica or alumina particles and then drying the resultant mixture at 80° C. for 12 hours to evaporate water. Patent Document 6 discloses a deodorant using no succinic dihydrazide, and containing 4 to 12% by mass of carbohydrazide and/or adipic dihydrazide, 1 to 5% by mass of hydroxylamine sulfate, 0.1 to 0.5% by mass of smectite, and 82.5 to 94.9% by mass of water. Patent Document 6 discloses that the reason why succinic dihydrazide is not used is that it contains a large amount of hydrazine, which is positive for mutagenicity, as an impurity. The present inventor has found a problem in that even when the organic acid dihydrazide is negative for mutagenicity, an inorganic compound carrier having supported thereon the dihydrazide may be positive for mutagenicity.
With respect to a deodorant which undergoes a chemical reaction with an aldehyde to exhibit a deodorizing function, such as a hydrazine compound, when the deodorant is solely used, the efficiency of contact of the deodorant with aldehyde gas is low so that the deodorant cannot exhibit high deodorizing performance. Therefore, a method has been proposed in which the deodorant is supported on various inorganic compounds so that the deodorant easily exhibits aldehyde deodorizing performance. However, it has not been known that there is a possibility that, in the inorganic compound carrier having supported thereon the hydrazine compound which itself is negative for mutagenicity, a part of the hydrazine compound is decomposed due to the carrier used or the supporting conditions during the step for supporting, so that the mutagenicity becomes positive.
In the end use of the above aldehyde gas deodorants, there are many products that a person in a living space is frequently in contact with in a daily life, for example, fiber products, e.g., clothes and bedding for preventing a body odor of aged person, such as nonenal, a car mat for preventing VOC, and interior products for preventing tobacco odor. Further, there is a possibility that even a product to be incorporated into an apparatus, such as a filter for an air conditioner, is in contact with a human body when replacing the filter with another, or fibers constituting the filter are removed and blown away and inhaled by a human body and hence, similarly, there should be the consideration of the safety. Therefore, an aldehyde gas deodorant, which has high aldehyde deodorizing performance and which is negative for mutagenicity, is desired, but an aldehyde gas deodorant which satisfies the requirement has not yet been obtained.